A person is able to see objects clearly only when these are lying at distances between 50cm and 300cm from his eye.

i. What kind of defects of vision he is suffering from?

ii. What kind of lenses will be required to increase his range of vision from 25cm to infinity? Explain briefly.

(i) When the person is able to view objects placed at close distances clearly then the medical condition diagnosed will be myopia. Myopia is also known as short-sightedness or near-sightedness.

In a normal eye, the light focuses on the retina. With myopia, the eye is too long and focuses light in front of the retina, thus forming a blurred image.

(ii) To correct Myopia i.e. short -sightedness, corrective lenses should be used.

To increase the range of vision from 25cm to infinity a concave lens should be used in front of the eye lens which will diverge the rays coming from infinity, and the eye lens will converge the rays and thus forming the image on retina and not in front of it.

(Correction of eye affected by myopia)